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  <script>
    const item = new Set([1, 2, 3, 4, 5, 5, 5, 5]);
    item; //Set(5) {1, 2, 3, 4, 5} //返回结果是唯一  不重复的  
    typeof item; //"object"
    Object.prototype.toString.call(item); //"[object Set]"


    //   去除数组的重复成员
    array = [1, 2, 3, 1, 2, 4, 5, 6, 7];
    [...new Set(array)]

    //常用于数据集合操作（并集、差集 、交集、...）参考链接如下
    //https://zhuanlan.zhihu.com/p/457005328

  </script>
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